I had this one type of filter that was for a 20 gallon an dit cost me 80 dollars. I put it in( with old filter meadia from 30g and my water was never crystal clear, so I took it back and got the same one again, same issue, so then I bought another one of the same type and the same issue occured( I also had poor water quality acording to my chemical test kit) . So then I bought a bio-wheel water was crystal clean, no noise, good water flow, water quality turned good over a few days of running my new bio-wheel. You should check out there website and see why they are the best.